I made a table runner for a friend at work and used a Frixion pen and then ironed out the lines. I brought the table runner into work (I take a train and then walk several blocks to work). It was winter and by the time I got to the office I was shocked that most of the lines came back. I washed the runner and the lines did come out.
After that I never used the pen for any marking in an area you could see.